We are extending the study of certain diamino acids to try to identify and locate the energetic gradients to account for the remarkable uphill nature of their Na ion-independent transport. We will investigate their transport in various cells to discover the scope of this behavior. We are trying to interpret also the basis for the unusual asymmetry in the transport of alpha,alpha-dialkyl amino acids. The cotransport of H ion with these amino acids and with ordinary amino acids is under study. The membrane activity catalyzing the cleavage of ATP stimulated by the presence of these and other amino acids will be further characterized to see if it may be correlated with physiological transport. The role of ionophores in potentiating this stimulation will be studied.